1. Field of the Invention
The present invention relates to surface mounting of integrated circuits for use in connection with the manufacture of circuit boards. The surface mount circuit assembly comprises a breakaway support structure which has particular utility in connection with small footprint, high volume, pick-and-place surface mount devices and integrated circuit chips with power demands that require low-profile components and high core window density.
2. Description of Related Information
Early methods of circuit board integration and design used standard multi-layer board construction. Multi-layer construction is a chemical process. The process results in imprecise resistance and limits the amount of copper that can be used in the core window. Additionally, a pre-preg, or B-stage material, is used to adhere the multiple layers together, and resin from this material is used to fill voids left by the etching process and to prevent isolation breakdown between primary and secondary windings. Because of interleaving, the use of resin as fill material is often unavoidable. Consequently, the multi-layer board becomes a mix of the conducting material, which is usually copper, and the pre-preg. Once a header or molding compound is added above and below the multi-layer board, as much as 65% of the window may be non-copper.
Additionally, all electrical contacts emanating from a board must constitute a planar surface for surface mounting to a level surface. When surface mount leads are on different edges of a board, the board must be unitary or otherwise secured to maintain the leads on a single plane. Current designs use a unitary design, or connect sections of the board across the build area. Connectors across the build area occupy space that could be used for copper, adding more material and height to the design.
Current state-of-the-art circuit board design requires low-voltage, high-current power supplies. Overall board height requirements have not increased, so low-profile power supplies are also required, and the amount of fill should be kept to a minimum. To efficiently conduct high-current, low-voltage power to chips on a board, the core window should primarily be comprised of a conductor, rather than resin or adhesive. Additionally, such a structure must allow a low profile component.
A need exists, therefore, for an apparatus that allows a material with greater conductivity to be used in the core window and that minimizes the header footprint for a low profile. A need also exists for an apparatus to prevent the header or molding compound from entering the core window or otherwise decreasing the conductivity of the core window.
The apparatus of the present invention overcomes the above-mentioned disadvantages and drawbacks which are characteristic of the related information. The method of the present invention eliminates or minimizes the need for pre-preg, or B-stage material, and prevents board supports from occupying space that could more efficiently be used by conductor material, allowing greater conductor content in the core window, and allowing the core window to reside lower relative to the board. The apparatus of the present invention allows for a header to be used in the manufacturing process of a core assembly, but prevents the header from limiting the space in the core window of the core assembly.
The present invention employs a header with breakaway support rails. The support rails facilitate assembly of the unit, but are removable to minimize the height and footprint of the assembly. The breakaway support rails allow the use of the core window to be maximized for a given core assembly height.
Additionally, a plurality of prefabricated conductors are enclosed in an insulating material and positioned around a core post in the core window. Each prefabricated conductor mounts to two or more of the connector pins, thereby creating an electrical connection between the pins so connected. The prefabricated conductors allow a precise connection of known resistance, facilitate assembly, and minimize the use of pre-preg. Such prefabricated conductors are known in the art, but the use of such prefabricated conductors minimizes the stack height of conductors within the core window, further minimizing the height of the assembly.
Numerous objects, features and advantages of the present invention will be readily apparent to those of ordinary skill in the art upon a reading of the following detailed description of presently preferred, but nonetheless illustrative, embodiments of the present invention when taken in conjunction with the accompanying drawings.